ColoradoCarry chains now
Sept 1 - May 31: every CMV must CARRY chains, statewide
Must carry: 09-01 to 05-31
Since the August 2024 update, all commercial vehicles must carry chains or approved alternate traction devices from September 1 through May 31 on all state, federal and interstate highways - not just the I-70 high country. A CMV here means a GVWR or GCWR of 16,001 lbs or more, or designed to carry 16+ passengers including the driver. When CDOT activates the CMV chain law, you must have chains or ATDs on at least four drive wheel tires (buses: two).
Penalty — $100 fine plus a $32 surcharge for failing to carry. Substantially higher if an unchained vehicle blocks the highway.
CRS 42-4-106(5)
State DOT source →MontanaOut of season
Oct 1 - Apr 30: carry chains if over 26,001 lbs
Must carry: 10-01 to 04-30
Commercial vehicles over 26,001 lbs must carry snow tires and chains from October 1 through April 30 and fit them when weather or posted signs require. Chain-up is most often called on I-90 over Homestake Pass and Lookout Pass and on other steep grades.
Penalty — Fine, plus liability exposure if an unchained vehicle causes a crash or closure.
Montana DOT winter equipment rules
State DOT source →UtahOut of season
Oct - Apr: carry chains on designated routes
Must carry: 10-01 to 04-30
Utah's Traction Law requires commercial vehicles to carry chains between October and April when travelling designated routes. When UDOT enforces the chain law, trucks must fit chains on at least two drive wheels. Class I traction requirements apply to vehicles over 12,000 lbs GVW, and tires need at least 5/32 inch of tread.
Penalty — Citation; vehicles are turned back at the canyon mouth or route entrance.
Utah Admin. Code R920-6
State DOT source →WashingtonOut of season
Nov 1 - Apr 1: carry chains if over 10,000 lbs GVWR
Must carry: 11-01 to 04-01
From November 1 to April 1, every vehicle or combination over 10,000 lbs GVWR must carry sufficient chains at all times on designated mountain routes, regardless of road conditions or advisories. You must also carry two spare chains. Plastic chains are not accepted. Designated routes include I-90 between North Bend (MP 32) and Ellensburg (MP 101), SR-20 Tonasket (MP 262) to Kettle Falls (MP 342) and Newhalem (MP 120) to Winthrop (MP 192), and SR-155 Omak (MP 79) to Nespelem (MP 45). Local deliveries that do not cross the pass are exempt.
Penalty — Infraction; vehicles without chains are turned around at the pass.
WAC 204-24-050
State DOT source →CaliforniaWhen posted
No season - but you must carry chains to enter any chain-control area
No fixed season — triggered by posted signs
California posts chain controls by level rather than by date. Every vehicle, including four-wheel and all-wheel drive, must carry chains to enter a posted chain-control area. R1 requires chains on all vehicles except passenger vehicles and light trucks under 6,000 lbs with snow tires on at least two drive wheels. R2 exempts only 4WD under 6,500 lbs with snow tires on all four. R3 requires chains on every vehicle, no exceptions. On a semi-trailer only one set of chains is needed regardless of axle count; none on a tag axle; trucks on super singles must chain all drive wheels. Minimum mud-and-snow tread is 6/32 inch.
Penalty — Citation, and Caltrans or CHP can refuse entry to the control area.
CVC 605
State DOT source →IdahoWhen posted
Chain requirements on Lookout, Fourth of July and Lolo passes
No fixed season — triggered by posted signs
When the Idaho Transportation Department determines conditions are unsafe on Lookout Pass or Fourth of July Pass on I-90, or Lolo Pass on SH-12, it can require chains on all commercial vehicles using those routes. Commercial vehicles must fit chains on at least one tire each side of one drive axle, plus one axle at or near the rear of each towed unit.
Penalty — Citation under the motor vehicle code.
Idaho Code 49-948
State DOT source →NevadaWhen posted
No carry mandate - chain up wherever signs require it
No fixed season — triggered by posted signs
Nevada does not require commercial drivers to carry chains at any time of year, but drivers must chain up on any street or highway in the state when icy or snowy conditions trigger a posted requirement, as shown on roadside message signs.
Penalty — Citation under the rules of the road.
NRS 484D.520
State DOT source →OregonWhen posted
Chains required when ODOT posts it - traction tires do not count over 10,000 lbs
No fixed season — triggered by posted signs
Oregon signs conditional and mandatory chain requirements rather than running a fixed season. If your vehicle is towing or rated over 10,000 lbs GVW you must use chains, not traction tires. A single-drive-axle vehicle needs chains on one tire each side of the drive axle; a tandem-drive vehicle needs two tires each side of the primary drive axle, plus chains on the rear semi-trailer axle on B-train and C-train combinations.
Penalty — Class A traffic violation for failing to carry and use chains.
ORS 815.140
State DOT source →WyomingWhen posted
No carry mandate - but Level 2 on I-80 is common and costly
No fixed season — triggered by posted signs
Wyoming law does not require commercial vehicles to carry chains at any set time of year; the requirement switches on when WYDOT declares a level. Level 1 (hazardous) allows chains, adequate snow tires, or all-wheel drive. Level 2 (extremely hazardous) requires commercial vehicles to chain at least two drive wheels at opposite ends of the same drive axle. On I-80 it is most often called at the Three Sisters (MP 7-34), Walcott Junction (MP 235) and Summit (MP 318).
Penalty — $250 for a chain-law violation; $750 if the violation causes a highway closure.
WYDOT chain law
State DOT source →